These types devices are subdivided in many cases into at least two subsections, so that a pre-tensioning between the subsections is achieved for example by a spring pressing the two subsections away from each other and thereby pre-tensioning the conveyor chain mechanically. This pre-tensioning is necessary since a device of this nature is subject to high levels of wear and tear, especially at high conveyor speeds. The chain links tend in such cases to vibrate very sharply in some cases while circulating and this means that the smooth movement of the conveyor and or guide rollers of the conveyor chain in the guide profiles provided for the purpose is no longer guaranteed and the wear and tear is increased as a result. The pre-tensioning of the two subsections mentioned above acts through a pre-tensioning of the conveyor chain against any vibrations which might occur, but too great a pre-tensioning can even increase the wear.
DE 103 23 910 A1 proposes a magnetic chain guide for conveyor chains in which the magnets are provided for creation of a magnetic field in order to exert a magnetic force on the chain and thereby to attract the latter towards the guide rail. This enables undesired vibrations of the conveyor chain to be effectively damped down, so that under some circumstances even a pre-tensioning of the chain is unnecessary and the revolving device can thus be designed in one piece.
Patent application DE 10 2004 023 B4 discloses is a chain guide for an endlessly circulating conveyor chain. In such case the chain elements have conveyor rollers and guide rollers, with the conveyor rollers moving items along conveyors and the guide rollers being guided in a guide slot. The guide rollers are supported in such cases by means of a shaft bolt which protrudes through the guide rollers. In order to damp down vibrations of the chain magnets are provided at the base of the slot profile which act on the shaft bolts and thereby attract the chain links towards the base of the slot profile. In the proposed device the magnetic circuit is made via an air gap above the shaft bolts with the shaft bolts also directing and the field reflux back the magnets.